Compression testing device for thin materials



May 30, 1944- w. P. MONTGOMERY 2,350,060

COMPRESSION TESTING DEVICE FOR THIN MATERIALS Filed Oct. 22, 1942 Patented May 30, 1944 UNITED -s'rA'rr-:s PATENT orrlcs COMPRESSION TESTING DEVICE FOR THIN MATERIALS Wiley P. Montgomery, Washington, D. C., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application October 22, 1942. Serial No. 462,916

6 Claims. (Cl. 265-12) overcome this dimculty. it has been customary to to be made on a relatively thin specimen such asa single thickness of sheet of any desired 'metallic or non-metallic material. A further object is to provide an improved compression specimen holder for a relatively thin sheet specimen whereby a high degree of lateral stability is obtained together with accurate and sensitive determination of the strain characteristics of the thin specimen.

A further object is to provide an improved com` pression specimen holder for relatively thin sheet specimens that is relatively simple and inexpensive in construction, operation and maintei nance and that will permit a specimen to be inserted or removed with ease and dispatch.

Other objects and advantages will be more apparent to those skilled in the art from the following description oi' the accompanying drawing in which:

Fig. 1 is a perspective of my holder for making compression tests showing the specimen in position;

Fig. 2 is a sectional view of my improved holder shown in relation' to the usual compression loading platens of any suitable materials testing machine;

Fig. 3 is a perspective of one guiding jaw of my improved holder: and g Fig. 4 is a fragmentary transverse sectional view showing the manner in which the specimen is centered between the guiding Jaws.

In the particular embodiment oi' the invention disclosed herein. I have shown a frame or housing l of any .suitable height and depth provided with a vertical recess 2 which is preferably machined starting from the front surface of the frame. A pair of bars 3 and 4 extend across the open front face of the recess and are rigidly secured tothe frame I by screws 5 or other suitable means. Disposed with recess 2 are a pair of vertically elongated and slidable backing blocks 8 and 'l preferably T-shaped in cross-section. These blocks are preferably slightly longer than the height ofA housing I so that they normally project above the upper surface thereof when the frame and blocks are both flush on the loading table of a testing machine. The backs of the blocks bear against the end walls of recess 2 while each of the inner ends of the T stems support 'a series of rollers 8 and 9. A relatively thin elongated specimen Ill is placed between the opposed sets of rollers 8 and 9 which are brought into guiding contact with the specimen by adiustment of a pair of screws ll and I 2 threaded in the end of frame I and preferably terminating in a vertical groove I3 in the rear surface of one of the backing blocks 6. This groove prevents accidental displacement of the backing block. The two series of rollers are specifically shown as being supported by relatively small and independent spring clips I5, the rollers having small trunnions pvotally supported in the outer ends of the clips while the inner ends of the clips are iirmly held to the backing blocks by pairs o! clamping strips I6 and Il secured in position by screws. The foregoing manner of supporting the rollers in spring clips is the invention of R. L. Templin and therefore does not per se constitute a part of my invention. However, instead of clips, I have heretofore held the rollers in position by heavy grease such as vaseline and with the rollers so held in position the specimen can be inserted in the space between the rollers in the manner shown in' Figs. 1 and 2.

If it is necessary to transversely center the specimen lll two opposed upper screws I8 and Il' may be threaded through strip 3 and through the back side of housing I to engage the specimen and bring it to its central position. A similar ser of screws is also provided at the lower end of the specimen. With the thin specimen,inserted in the holder in the manner shown the whole de-` vice is then placed upon a lower platen 2li of any suitable loading apparatus such as a materials `testing machine whereupon a downwardly moving upper platen 2l applies a compression load to the upper end of specimen I0. As the compression load is applied the specimen is free to deform in a straight vertical line in accordance with its strain characteristics. During this com pression load the specimen is restrained from bending laterally by the rollers I and I bearing its length so that a true strain measurement can be obtained. The extent oi' actual deformation is relatively small and hence the rollers and their supports are adapted to allow suilicient rolling action oi' the rollers during a compression operation thereby avoiding any slipping of the rollers about a fixed point. It will be understood that the rollers are suiilcientiy spaced to insure i'reedom of action and yet are close enough to impart the necessary lateral stability to the specimen.

Ii.' desired. suitable strain gauges may be applied to the specimen and these may be supported upon rods such as 22 and 23 suitably mounted upon the housing I. The spacing between the bars 3 and 4 and a similar cut-out spacing in the back of the frame I permits strain:

gauges to be brought into gauge point contact with the edges of the specimen.

From the vforegoing disclosure it is'seen that I have provided a very compact, simple and eilective means for making a compression test of a relatively thin specimen of such length that it ds not have suillcient lateral stability to permit a compression test to be made directly thereon. Also my improved device is highly accessible and durable together with a. high degree oi.' accuracy and sensitivity.

It vwill o1' course be understood that various changes in details of construction and arrangement of parts may be made by those skilled in the art without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. A device for making compression tests of a relatively thin specimen comprising, in combination, opposed rolling'l means whose rollingl axes extend transversely of the direction of movement of the specimen, said means being spaced apart to receive and laterally engage a relatively thin specimen during application of a compression load thereto, and means for maintaining said opposed 'rolling means in their operative position.

2. A device for making compression tests of a relatively thin specimen comprising, in-combination. a trame. a pair of vertically extending backing membersl supportedy by said `iframe in spaced relation to each other so as to receive arelatively thin specimen and laterally support the same during application of a compression load thereto, and rollers extending transversely of the direction -of movement of the specimen, said rollers beinginterposed between each side of the specimen and said backing members to allow rel-- atively tree strain deformation of the specimen.

3. The combination set forth in claim 2 further characterized in that said backing members are substantially T-shaped in cross-section with the base of the 'l' supported against theirame and the stems of the Ts being directed toward the specimen.

4. The combination set forth in claim 2 further characterized by-the provision of means for varying the spacing between the backing members so as to accommodate specimens of differentv thickness.

5. The combination set forth in claim 2 iurther characterized by the provision of means for transversely centering the specimen.

6. A device for making compression tests of a relatively thin specimen comprising, in combination, a trame having a vertical recess that is accessible from its upper and lower ends and its sides, a pair of backing blocks vertically movable in said recess andnormally spaced apart to receive a compression specimen, and rotatable antifriction means whose rotatable axes extend transversely of the direction of movement of the specimen, said rotatable means being interposed between each side of said specimen and the adjacent ends of said blocks thereby to allow strain deformation of the Specimen during compression loading thereof while laterally stabilizing the specimen.

' WILEY P. MONTGOMERY. 

